mindmap
root((手段))
mean
now usually in the plural means, is very general and may apply to anything or anyone that serves an end: had no ~s of traveling but his own two feet.
instrument
as applied to persons, implies a secondary role, sometimes as a tool, sometimes as a dupe: used him as the ~ of her ambitions; and, as applied to things, is likely to suggest a degree of fitness or adaptation for use as a tool: politics, a powerful ~ for change.
agent
applies to a person who acts to achieve an end conceived by another: dealt with a real estate ~; or to a thing that produces an immediate effect or definite result: salt, an ~ in the melting of ice.
medium
applies to a usually intangible means of conveying, transmitting, or communicating: resorted to sign language as a ~ of communication.